1. Field of the Invention
Embodiments of the present invention relate to an apparatus, medium, and method controlling a disk drive, and more particularly, to an apparatus, medium, and method for controlling a flying height of a magnetic head of a disk drive so that a clearance between a disk and the magnetic head in a data write mode is similar, e.g., substantially the same, as that of the magnetic head in a data read mode.
2. Description of the Related Art
Conventionally, as in U.S. Patent Publication No. 2002-122268, a shape memory alloy has been used to prevent a head and a disk from contacting each other due to a thermal pole tip protrusion during a temperature rise. Similarly, Korean Patent Publication No. 2004-52031 discusses the controlling of a write current by measuring the thermal pole tip protrusion of a magnetic head.
Here, in general, disk drives, such as hard disk drives (HDDs), which can be data storage devices for computer systems, typically reproduce and/or write data on a disk using a magnetic head. Due to the recent trend of high capacity, high density, and compact HDDs, there has been a corresponding increase in bit density in a tangential direction measured in bits-per-inch (BPI) and track density in a radial direction measured in tracks-per-inch (TPI), thereby requiring more delicate operations relative to the control of the HDDs.
A magnetic write head of an HDD may be made of a metal material, and a slider supporting the magnetic head may be made of a non-metal material. When a write current flows through a coil, during a data write operation, heat is generated according to Joule's law. At this time, a pole area expands due to a thermal expansion coefficient difference between the metal material and the non-metal material, which has been referred to as thermal pole tip protrusion (TPTP). Due to the TPTP, there is a reduction in the flying height of the head, that is, a clearance between the head and a disk.
Accordingly, the flying height of the magnetic head in a write mode is different from a flying height of the magnetic head in a read mode. Consequently, servo pattern signals reproduced in the write mode and the read mode have different magnitudes, thereby affecting the servo control performance of the HDD. Also, since the thermal pole tip protrusion does not occur perfectly during a starting point of the write operation, write errors may occur, and more frequently at low temperatures.